Biosecurity and disease
prevention
Production goals
– optimal performance, product quality, disease
prevention and control
Disease prevention
strategies
Fish condition
Probiotics & antioxidant
protection help maintain
balance
Optimizing growth and
performance
Balance
Environment
Pathogen
Imbalance leads to the development of disease
through opportunistic pathogen attack
Husbandry and system stability affect
stress response and health
• Direct link between stress parameters and
survival and health status (Varsmos et. al. 2005)
• Variable water temperature can trigger dramatic
changes in immune status and susceptibility to
virus.
• Tank cleaning caused short term acute stress
and increased plasma osmolality, decreased IgM
levels
• Short periods of sub-clinical disease challenge
affect life-long productivity
• Early control of sub-clinical disease challenges
is therefore extremely important
THE DISTRESSED FISH
Immune Fn
Blood pressure
Gill damage
Pathogen attack
J Halver
Critical point identification in a hatchery
environment
Visitors & workers
Water
Procedures
Monitoring
Audits/inspections
Wild fish
Quality control / assurance
Feeds
Waste water
Live food
Pellets
Fry
Eggs & Larvae
Hatchery
Certification
Market size fish
Broodstock
Inspections process
Certification
Systems layout
Equipment
Dead / moribund fish
Training of personnel
Identifying Hygiene problems
1. Do you have hygiene plan ?
a) Hygiene in the farm
b) Hygiene outside the farm
2. Do you have a specific hygiene manual?
a)
b)
c)
d)
e)
Poster display
Hygiene training
Hygiene information file
Hygiene document
Hygiene team
3. For a new worker do you have specific hygiene training ?
4. Do you limit worker and visitor circulation within the farm ?
5. Have you hand washing facilities?
6. Have you special workers clothes?
7. Do you regularly clean equipment and clothes ?
HACCP Principles
HACCP is systematic approach to the
identification, evaluation, and control of good
safety hazards based on the following seven
principles:
Principle 1: Conduct a hazard analysis
Principle 2: Determine the critical control points
(CCPs)
Principle 3: Establish criticals limits
Principle 4: Establish monitoring procedures
Principle 5: Establish corrective actions
Principle 6: Establish verification proceedures
Principle 7: Establish record-keeping and
documentation procedures
Departmental organisation
• Reception – Storage – Expedition
• Monitoring of water quality
• Cleaning and disinfection of all the fish farm
equipment and tanks
• Aquaculture team
• Visitors
• Farm inlets: Lorry, eggs, broodstock, juveniles....
• External animals (rates, cats, dogs)
• Farm outlets: Juveniles, eggs, dead fish...
• All the departments of the fish farm should be
looked at
Development of hygiene and biosecurity plan and
protocols
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Water reserve
Pump station
Broodstock
Egg Incubation
Larvae
Weaning
Nursery
Live food
Feed storage
Development of hygiene and biosecurity plan and
protocols
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Office administration
Workers facilities
Global Hygiene management
Ongrowing
Growing
Packaging
Fish farm Access
Global environmental analysis:
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Geographical point
Potential pollution
Sea water currents
River influence
Fish farm “auto-pollution”
Biology of immune system
development
Some viral diseases of aqua & poultry
DNA
viruses
RNA
viruses
Virus family
Poultry
Aqua
Herpesvirus
Marek’s, Duck VE
O. masou virus
Pox virus
Fowl pox
Circovirus
CAV, PBFD
Nimavirus
WSSV
Iridovirus
EHNV
Baculovirus
HB, SEMBV
Birnavirus
IBD
IPN
Reovirus
Viral arthritis/malabsorption
Aquareovirus
Coronavirus
Infectious bronchitis
YHV
Picornavirus
Duck viral hepatitis
TSV
Retrovirus
Avian leukosis
Orthomyxoviru
s
Avian influenza
Paramyxoviru
s
Newcastle
Rhabdovirus
Infectious salmon anemia
IHNV, Spring viremia, VHS
To limit disease impact:
The inflammatory response must
be quickly controlled!
• Minimize damage to
surrounding tissues
• Faster healing
• Reduced impact of
the infection on
health and
performance
Crustaceans rely on
innate immunity
Types of pathogens
Viruses
All RNA and DNA viruses
Bacteria
Salmonella spp.
Campylobacter jejuni
Listeria monocytogenes
Mycobacterium spp.
Brucella abortus
Lawsonia intracellularis
Erysipelothrix rhusiopathiae
Corynebacterium pseudotuberculosis
Pasteurella multocida
Staphylococcus aureus
Pneumocystis carinii
Shigella spp.
Rickettsia typhi
Yersinia pesti (causes plague)
Protozoa
Eimeria spp.
Cryptosporidium spp.
Leukocytozoon spp.
Leishmania spp.
Toxoplasma gondii
Trypanosoma cruzi (Chagas Disease)
Plasmodium spp. (cause malaria)
Yeast and fungi
Candida albicans
Cryptococcus neoformans
Aspergillus spp.
Histoplasma capsulatum
*Human pathogens
Microbiology
Disease resistance enhancement
Nutritional strategies for improving
health
New tools for improving
production
Stress management
Microbiological control – water
quality, environment and live feed
Prebiotics & probiotics in live feed
and dry diets
Nutrition - mineral dependant
enzyme pathways, ARA etc
So what are
you thinking
of trying on
me today ?
An immunomodulator is a substance which has an effect on the immune
system.Immunostimulants or immunosuppressants)
Immunostimulants
• Increase disease resistance by improving host
defensive mechanisms against opportunistic
pathogens
There are two main categories of immunostimulants:
• Specific immunostimulants are those which
improve specific immune response, such as
vaccines or any antigen.
• Non-specific immunostimulants are those which
help general immune response such as adjuvants
and non-specific immunostimulators.
• Enhance specific immune responses and nonspecific mechanisms
immunostimulants or immunosuppressants
• Stimulate macrophages and dendritic cells
located in gut tissue
• No memory component
• Short duration effect
• B glucans, peptidoglycans,
lipopolysaccharides, nucleotides – type of
polysaccaride
• Should not be fed continuously
Probiotics
• Live microbial feed supplements which help
the fish by improving its intestinal microbial
balance
• Can compete with pathogenic bacteria in the
gut for space and nutrient, can produce
antimicrobial substances and change
intestinal environmental conditions
• Probiotic bacterial cultures are intended to
assist the body's naturally occurring gut
flora, an ecology of microbes, to re-establish
themselves.
Vaccination – dip and injection
Vaccination response - fish
• Fish have a range of adaptive immune
responses and immune memory, involving B
cells and T cells, antibody and phagocytic
cells.
• This adaptive immune response enables
them to specifically “remember” exposure to
pathogens and respond with increased
efficiency on subsequent exposure, forming
the basis of vaccination
• Understanding of these immune mechanisms
and how the pathogens interact has allowed
aquatic animal health scientists to develop
successful vaccines.
Vaccination response - shrimp
• Widely thought that invertebrates do not have
an adaptive immune response.
• Thus vaccines have not been routinely
developed and used in shrimp aquaculture
• Invertebrates have generalized immune
responses to invading pathogens such as
bacteria and fungi.
• There is increasing evidence for a specific
immune memory in crustaceans, including
shrimp and that the diversity and sophistication
of responses in invertebrates is far greater than
previously assumed
Vaccination of fish
Developed in 1990’s for salmon
farming
Vaccines for farmed fish are
• Injectable and oil adjuvanted
• Aqueous immersion vaccines
– Used for juvenile stages to offer
protection prior to injection
• Oral vaccines
– available commercially
– variable success as primary
immunogens
Dip vaccination of fry in the hatchery
Dip vaccination of fingerlings
Anaethetic
Dip vaccination of fish
Injection vaccines
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Appears impractical for thousands of fish
Adopted by salmon farmers
Extremely effective
Stress can be managed with use of
anaesthetics
• Skilled vaccinators can inject high
numbers of fish per day
Injection vaccination of fish
• When the fish are large enough to be
individually handled (>50g average weight) they
can be vaccininated by injection
• Fish are crowded into a small area and are
anaesthetised since the larger the fish the
greater the risk of self-injury due to stress
reactions..
• A measued dose of vaccine (usually 0.1ml to
0.2ml) is injected in the abdominal area of each
fish held with the ventral side up and the head
away from the operator΄s body. The needle is
inserted into the peritoneal cavity at a 45o angle
to a depth of approximately 0.5 cm. Automatic
injection guns or syringes are used.
Injection vaccination of fish
Pond and tank biosecurity - equipment
Tank hygiene and daily cleaning for
maintaining optimal tank conditions
Hatchery biosecurity
Health and hygiene
• Autoclave
• Drying oven
• Microwave
Biosecurity - Biological materials
Biosecurity - Visitors
When visitors to the farm are expected, consideration of
relative risks allows you to develop and use practical
biosecurity measures.
Low-risk visitors - Visitors from villages or towns who have
no contact with fish farms present very little risk of carrying
diseases.
Moderate-risk visitors - People who routinely visit fish farms
but have little or no contact with the fish or culture water such
as salesmen and delivery people present only a moderate
risk of introducing disease.
High-risk visitors - High-risk visitors include veterinarians,
shrimp suppliers or shrimp buyers, neighbouring farmers, and
anyone else who has close contact with fish or fish farms.
Visitors should wash their hands and feet.
Equipment and instruments that have direct contact with fish
should be cleaned and disinfected before and after use.
Biosecurity - Vehicles
There is a risk of transferring disease between safe
zones by vehicles especially vehicles transferring
stock or equipment between farms or other facilities.
Vehicle tyres and undercarriages should be cleaned
with freshwater.
Cleaning of small equipment
Disinfection baths
Equipment in daily use can be stored in disinfection baths
but should be rinse well before use. All baths should
be changed weekly or when dirty ( which ever is
sooner).
1. Live food production equipment (airtubes /pipettes
etc.) should be left in hydrochloric acid baths (pH 2)
which should be changed weekly.
2. Fish handling equipment e.g. hand nets/ tank cleaning
equipment etc. can be stored in iodophor baths or
hypochlorite (Chlorine can degrade hand nets).
3. Footbaths or foot-mats should be set-up at hatchery
entrances.
Cleaning of large equipment
1.
2.
3.
4.
Hose down with fresh water to remove major fouling.
Add detergent to warm water and remove encrusted
fouling with a brush or abrasive pad (e.g. Scotch brite).
Rinse with fresh water.
Disinfect equipment with iodophor or similar if
equipment was in previous contact with diseased fish.
Rinse and store dry if not being used immediately.
Work bench surfaces etc. should be wiped with
hypochlorite periodically and floors should be sprayed
with hypochlorite at least once a week.
Vehicles
Vehicles
1. Vehicles from other farms
should not be allowed into the
fish holding areas. The tyres
and body work should be
disinfected using a high
pressure hose with disinfectant
added.
2. The tanks of all fish transport
vehicles should be thoroughly
cleaned and disinfected as in
equipment cleaning before
being stocked.
Mortality disposal
All mortalities should not flushed away through the farm
effluent system.
They need to be properly disposed of
For small quantities of mortalities fish can be
• buried in pits with lime,
• composted,
• incinerated
• bagged up and removed from the site as for normal
household domestic waste.
If the fish is rotten, some hypochlorite can be added.
Harvesting and Transporting Fingerlings
Recirculation, water maturation
Bacteria dynamics
high
low
LowBackground
level of bacteria
Stabilising effect
• Probiotic bacteria give water stability
high
High background
level of bacteria
low
Bacterial control in larvae tanks
Possibilities
• Maturation of incoming water
• Recirculation of water in larval tanks
• Bacteria replacements/substitutes
Water Maturation
• Larvae system
Water
Treatment
Biofilter
Water recirculation
• Larvae tanks
BF
SF
UV